Spec::Rails, "model.should have(1).error_on(:attribute)" passes when?

Spec::Rails people,
I’m curious about:

  • model.should have(1).error_on(:attribute)
    displayed in the URL below:
    http://rspec.rubyforge.org/rspec-rails/1.2.2/classes/Spec/Rails/Exten
    The Rspec peepcode screencast suggests that
    model.should have(1).error_on(:attribute)
    should pass if
    model.send(:attribute)
    returns nil
    For me, I get an exception from the rspec script.
    My work-around is simple.
    Instead of:
  • model.should have(1).error_on(:attribute)
    I Use:
    -model.send(:attribute).should be_nil
    But now I have the question:
  • What kind of error causes:
    • model.should have(1).error_on(:attribute)
    • to pass ??
      –b